Perioperative management of chronic respiratory disease.
Abstract: Respiratory disease contributes significantly to the perioperative challenges of surgery. Pre-existing pulmonary co-morbidities and respiratory complications can have profound effects on patient outcomes. Knowledge of these conditions and the potentially deleterious effects of anaesthesia and surgery can enable clinicians to optimise lung function, reduce complications and improve results.

KEYWORDS Surgery / Respiratory disease / Anaesthesia
Article Type: Report
Subject: Asthma (Complications and side effects)
Anesthesia
Medical research
Medicine, Experimental
Authors: Ihsan, Khan M.
Nannaparaju, Madhusudhan R.
Aftab, Syed
Khan, Wasim S.
Malik, Atif A.
White, Jonathan JE.
Pub Date: 10/01/2012
Publication: Name: Journal of Perioperative Practice Publisher: Association for Perioperative Practice Audience: Academic Format: Magazine/Journal Subject: Health; Health care industry Copyright: COPYRIGHT 2012 Association for Perioperative Practice ISSN: 1750-4589
Issue: Date: Oct, 2012 Source Volume: 22 Source Issue: 10
Topic: Event Code: 200 Management dynamics Computer Subject: Company business management
Product: Product Code: 8000200 Medical Research; 9105220 Health Research Programs; 8000240 Epilepsy & Muscle Disease R&D NAICS Code: 54171 Research and Development in the Physical, Engineering, and Life Sciences; 92312 Administration of Public Health Programs
Accession Number: 309315289
Full Text: Introduction

Respiratory diseases such as asthma and chronic obstructive pulmonary disease (COPD) are extremely prevalent worldwide. It is estimated that up to 17% of those aged over 65 worldwide have some form of obstructive airways disease (Diaz-Guzman & Mannino 2010). These co-morbidities significantly increase the risk of perioperative respiratory complications.

A large number of operative procedures take place worldwide and up to 25% of all complications in patients undergoing surgical procedures are associated with the respiratory system (Nice 2010). Even in healthy patients, anaesthetic and surgical intervention can cause significant respiratory compromise.

Normal breathing mechanics involve diaphragmatic and intercostal contraction with passive expiration due to an elastic recoil of the lungs and chest wall. In active or distressed breathing, accessory structures in respiration including neck, shoulder and abdominal muscles are involved (Cuschieri et al 2001). There are many factors which may lead to respiratory compromise during the perioperative period. Firstly anaesthesia, and medications used to achieve anaesthesia, affect not only the mechanics of breathing but also the neuro-chemical drive to breathe. This is due to the various anaesthetic and opiate drugs used which reduce the hypercapnic and hypoxic responses creating a net effect which can compromise respiratory function and lead to complications such as hypoxia, hypercapnia, dyspnoea, infection, pneumonia, pleural effusions and respiratory failure. Furthermore, surgery on the abdomen or chest itself, impairs function of the respiratory muscles and compliance of the chest wall and lungs.

Careful management of the respiratory system is essential to prevent these complications. The respiratory system must be carefully assessed preoperatively, then appropriately optimised, monitored and managed in the intra- and post-operative periods with great vigilance, especially for patients with pre-existing respiratory disease.

Preoperative assessment

A thorough history and general examination is essential to ensure safe and effective preoperative and perioperative respiratory management. History of any respiratory disease or symptoms should be actively sought, including hospital attendances and admissions. Information regarding shortness of breath, exercise intolerance, cough and history of smoking is important to uncover any underlying and undiagnosed respiratory conditions. Examination should include inspection, auscultation and special tests looking for wheeze, crackles, decreased breath sounds, or a prolonged expiratory phase indicating obstructive respiratory disease. The patient's general health status, functional status, work history, obesity, alcohol consumption, age, other medical history including interstitial lung disease, neurological impairment and immunosuppression should be given great importance to obtain an overall picture of the patient's health and fitness for surgery.

It is also important that smokers are identified at pre-assessment. Smoking is associated with significant complications of the respiratory system (Moores 2000). Smoking reduces muco-ciliary clearance and the immune response. Therefore infections are more common in smokers than in those who have never smoked. Smoking cessation is recommended before all surgical and anaesthetic procedures but it is unclear as to the optimal time frame for smoking cessation. It seems that at least four to eight weeks of smoking cessation is required for significant reductions in smoking related complications (Nakagawa et al 2001). However there is some evidence to suggest that there is also a paradoxical effect if smoking is ceased only a short time before surgery. This may be due to increased mucous production or possibly due to the abrupt end of the irritant effect of smoke and therefore a reduced cough response for mucous clearance (NICE 2010). Despite these considerations, it is still recommended that smoking cessation is pursued before surgery (Theadom & Cropley 2006). Patients who are given support for smoking cessation with pharmacological or psychological means, do better perioperatively than those who are not. Furthermore, patients who quit smoking six months before surgery have a risk similar to those who have never smoked, although there are still slight increases in risk until one year after smoking cessation in terms of postoperative pneumonia (Arozullah et al 2003).

Investigations form an important tool in the respiratory assessment of patients undergoing surgery. A preoperative chest radiograph is a very commonly ordered investigation. However evidence suggests that, unless there are risk factors, a routine chest radiograph should not be performed (Munro et al 1997). In a systematic review of the literature, Joo et al (2005) found that postoperative respiratory related complications were similar between patients who had had a preoperative chest radiograph and those who had not.

Pulmonary function tests (spirometry) may also be considered preoperatively. These tests specifically measure the amount (volume) and speed (flow) of air that can be inhaled and exhaled and are used to calculate the [FEV.sub.1]. This is defined as the forced expiratory volume in one second. However, the results are not predictive of postoperative complication rates (Smetana 2006) unless the patient is undergoing lung resection (NICE 2010). Therefore, these tests should be considered only if a patient is to undergo lung resection surgery or if any unexplained respiratory symptoms such as shortness of breath are found on pre-operative assessment.

Other investigations such as arterial blood gas have not been found to be useful in predicting postoperative respiratory complications (Fisher et al 2002) unless there is existing acute or chronic respiratory disease.

On the basis of all of the above information, an assessment can be completed regarding appropriateness for surgery and if necessary, any supportive treatment can be initiated at this stage to optimise the patient for surgery at a later date.

Optimisation and preoperative management of respiratory conditions

Patients with COPD are known to be at increased risk of respiratory complications including mortality (Fuster et al 2006). Therefore, patients with COPD must be optimised before surgery. Optimisation includes the use of bronchodilators, steroids and antibiotics. Chest infections or infective exacerbations of COPD are a relative contraindication to anaesthesia and surgery. National Institute for Health and Clinical Excellence guidelines for COPD (NICE 2010) state that spirometry should not be the sole criterion for assessment, but rather that a composite assessment tool, such as the American Society of Anaesthesiologists (ASA) classification system, which is the most commonly used risk stratification system should be used (see table 1). It is based on history, examination and preoperative findings. A patient with a higher ASA class has a higher risk of postoperative complications (Clague at al 2002) and more input is required to optimise that particular patient prior to surgery.

Patients with obstructive lung disease such as asthma should have their respiratory function optimised preoperatively. Ideally this would mean an absence of symptoms and a FEV1 of greater than 80% predicted or personal best (NICE 2010). Asthma is known to increase respiratory complications such as atelectasis and infection (NAEPP 2007).

An assessment for obstructive sleep apnoea (OSA) is also an important consideration during the initial anaesthetic assessment. OSA can lead to significant perioperative complications such as hypoxia, hypercapnia, difficulty in initial management, the need to re-intubate, obstructed airway and respiratory arrest with opioid usage (Cullen 2001, Gupta et al 2001). Often patients themselves are unaware that they have OSA. Clinicians should suspect OSA in patients with a history of snoring, daytime somnolence and sleep disturbance. OSA is more common in obese patients due to adipose tissue deposits in pharyngeal tissue. To anticipate difficulties that may be experienced during intubation of a patient with OSA the Mallampati score has been used (Mallampati et al 1985). This grades the oropharynx visually into four classes based on what structures are easy to see. A high score is associated with OSA and hence, difficulties during intubation. Patients with OSA may benefit from preoperative and postoperative continuous positive airway pressure management (CPAP).

Ultimately, the merits of surgery must be weighed against the risks on an individual patient basis by the anaesthetist and the surgeon.

Intraoperative management

Once the patient is prepared and ready for surgery, they will in most cases receive local, regional or general anaesthesia. Respiratory management in cases of local and regional anaesthesia usually include oxygen administration (with relative contraindications such as known respiratory co-morbidities kept in mind), pulse oximetry, and clinical assessment of the rate of breathing. Often talking to the patient and gauging their response is sufficient to confirm that the airway is patent and the patient is sufficiently alert to maintain their airway, breathe and communicate.

In cases of general anaesthesia, the patient is pre-oxygenated and either a laryngeal mask airway (LMA) or a more secure cuffed airway is placed carefully by the anaesthetist during induction of anaesthesia. Adequate placement is confirmed by inspecting the chest for bilateral equal chest movements and auscultation of air entry to both lungs or as deemed appropriate. Oxygen saturation is carefully monitored with pulse oximetry.

A carbon dioxide monitor (capnograph) is also placed near the airway to measure the concentration of expired carbon dioxide and to ensure that sufficient gas exchange is taking place in the lungs. Blood gas analysis can be performed intermittently to measure blood pH, partial pressures of oxygen or carbon dioxide and bicarbonate levels.

The method of anaesthesia employed is also thought to significantly affect respiratory morbidity. Even though it is generally thought that spinal or epidural anaesthesia is better than general anaesthesia, evidence suggests that it is the addition of a spinal or epidural anaesthesia to the general anaesthetic that contributes to the lower rate of respiratory complications rather than the avoidance of general anaesthesia alone (Rodgers et al 2000). When considering regional versus general anaesthesia in patients with obstructive airway disease, regional anaesthesia is more often recommended than general anaesthesia in order to avoid oral airway involvement (Haeck et al 2009). In addition, specific drugs used during anaesthesia also affect respiratory complication rates. Intermediate-acting neuromuscular blockers, such as atracurium or vecuronium, seem to be less detrimental than longer-acting neuromuscular blockers such as pancuronium (Groeben 2004).

Apart from anaesthesia and other pharmacological factors, surgery by itself is a traumatic experience, and there are a myriad of factors which influence the respiratory outcome and all must be kept in consideration. Distance of the surgical site from the diaphragm is known to be inversely related to respiratory complications (Arozullah et al 2003). Similarly, the longer the operation and anaesthesia time, the higher the rates of respiratory complications. Minimally invasive surgery (such as laparoscopic cholecystectomy versus open cholecystectomy) is known to carry a lower incidence of respiratory complications (Torrington et al 1996).

Patients known to have COPD or asthma may benefit from prophylactic preoperative and intraoperative beta-2 adrenergic agonists such as salbutamol to reduce the risk of bronchospasm. The administration of corticosteroids should also be considered depending on the patient's functional status, lung function tests, type of surgery and/or history of previous usage (Silvanus et al 2004). Volatile anaesthetic agents such as halothane and ultane are generally preferred due to their inhibitory effect on bronchospasm (Groeben 2004).

The administration of sedatives and opioid analgesics in OSA and COPD patients has to be undertaken with great caution (Haeck et al 2009). These drugs cause respiratory depression, inhibit airway muscle activity and depress pharyngeal tone, increasing the risk of apnoeic events. A regional or local anaesthesia is preferred generally. Narcotic analgesics should also be substituted with other drugs such as non-steroidal anti inflammatory drugs (NSAIDS), where appropriate. If unavoidable, use should be carefully titrated to pain and the patient monitored closely.

Pneumothorax is a complication that can occur as a result of barotrauma after general anaesthetic, other trauma (which may also be iatrogenic) or spontaneous. It leads to accumulation of air in the pleural space and can cause significant morbidity in otherwise well patients. Rates of pneumothorax are higher in cardio-thoracic surgery for obvious reasons and in patients who have COPD, possibly due to perforation of a pulmonary bullae. A pneumothorax can rapidly progress to a tension pneumothorax if, with each inspiration, air accumulates in the pleural space and does not escape - producing a one-way valve effect. This may lead to increased intrathoracic pressure, decreased venous return to the heart and ultimately to cardiac arrest. Therefore, one must be vigilant and continuously monitor chest wall movements, tracheal position, oxygen tension and the general state of the patient. Prompt action has to be taken (e.g. needle thoracotomy with subsequent chest drain) if necessary (Haeck et al 2009).

Postoperative management

In general anaesthesia, once the neuromuscular blocking agents are reversed, the patient is extubated once airway maintenance is ensured. A patient who coughs and pulls out their own airway gives a good sign that their airway is safe and extubation is appropriate. Whether regional or general anaesthesia has been used, respiratory monitoring postoperatively is important to ensure that the patients are adequately maintaining their airway and have adequate gaseous exchange. This is measured by pulse oximetry and ensuring oxygenation and ventilation respectively (Haeck et al 2009). Inspection of the patient, monitoring chest movements and listening for snoring are equally important. If there are any concerns, a simple manoeuvre such as a chin-lift or jaw thrust may be used with airway adjuncts such as an orophayngeal or a nasopharyngeal tube.

Early postoperative mobilisation of the patient is essential in all cases to prevent respiratory complications. Lung expansion manoeuvres, guided by physiotherapists and nursing staff, and continuous positive airway pressure (CPAP) in selected cases, are all useful methods to avoid respiratory complications (Overend et al 2001, Kindgen-Milles et al 2005).

Pain must be well controlled, especially if surgery involves the abdomen and thorax where pain can inhibit respiratory muscle activity. This can be achieved by patient controlled analgesia, epidural analgesia, oral analgesia with local anaesthesia administered at the end of surgery, or using other analgesic modalities postoperatively.

Conclusion

The ultimate clinical decision to proceed with surgery should rest with the consultant anaesthetist and consultant surgeon. The patient's co-morbidities need to be taken into account, their functional status and the necessity for surgery. If time permits, it is best to optimise the patient's medical conditions before surgery. This might include respiratory rehabilitation. It is best for the patient if a tailored programme is commenced to achieve individual goals, and a multidisciplinary approach used which includes physical training, disease education, and nutritional, psychological and behavioural intervention. This maximises the well-being of patients in the long term.

References

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by Khan M Ihsan, Madhusudhan R Nannaparaju, Syed Aftab, Wasim S Khan, Atif A Malik, Jonathan J E White

Correspondence address: Mr Wasim S Khan, Clinical Lecturer, University College London Institute of Orthopaedic and Musculoskeletal Research, Royal National Orthopaedic Hospital, Stanmore, London, HA7 4LP. Email: wasimkhan@doctors.org.uk

About the authors

Khan M. Ihsan

MB BS

Speciality Registrar, Ittefaq Hospital, Lahore

Madhusudhan Raj Nannaparaju

MBBS, MRCS

Speciality Doctor, University College London Institute of Orthopaedic and Musculoskeletal Sciences, Royal National Orthopaedic Hospital, Stanmore

Syed M. E. Aftab

MA (Cantab), MBChB (Edin), MRSC (Eng)

ST4 Trauma and Orthopaedic Registrar, Royal

National Orthopaedic Hospital, Stanmore

Wasim S. Khan

MBChB, MSc, MRCS, PhD

Clinical Lecturer, University College London Institute of Orthopaedic and Musculoskeletal Sciences, Royal National Orthopaedic Hospital, Stanmore

Atif A. Malik

MBChB, MRCS Ed, MSc (Ortho Eng)

Speciality Registrar, Royal National Orthopaedic

Hospital, Stanmore

Jonathan J. E. White

MBBS, BSc (Hons)

FY2 Doctor, Trauma and Orthopaedics, Luton and Dunstable NHS Foundation Trust

No competing interests declared

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Provenance and Peer review: Unsolicited contributed; Peer reviewed; Accepted for publication April 2012.
Class I    Normal, healthy patient without organic,
           physiological, or psychiatric
           disturbance

Class II   Controlled medical conditions without
           significant systemic effects

Class III  Medical conditions with significant
           systemic effects, intermittently
           associated with significant functional
           compromise

Class IV   Medical condition poorly controlled and
           associated with significant dysfunction
           and a potential threat to life

Class V    Critical medical condition associated
           with little chance of survival with or
           without the surgical procedure

Class VI   Brain dead and undergoing anaesthesia for
           the purposes of organ retrieval and
           donation

Table 1 ASA scoring system
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